Mechanical Performance Assessment of Bolted Glulam Joints with Local Cracks

Abstract

Cracks are commonly observed in glulam joints even though the members have yet to experience the design load level. The cracks are commonly formed by tensile stress perpendicular to grain and are induced by shrinkage of the wood under varying climatic conditions and exacerbated by the confinements from steel plates and bolts. The aim of this research was to investigate the effect of cracks on the behavior of bolted joints under tension load. A theoretical method based on a quasi-nonlinear fracture mechanics model was proposed to estimate the failure load of tension joints. Both bolt ductile yielding and brittle failure, such as splitting and plug shear of wood, were considered in the analytical calculation. To obtain the load distributions of total load on individual bolts, a three-dimensional (3D) linear elastic numerical model was developed. Furthermore, full-scale tension tests were conducted on glulam joints with different configurations and crack patterns to validate the proposed theoretical method. It was found that the analytical method can reasonably predict the capacity and failure modes of bolted glulam joints. Moreover, the experimental results indicate that cracks have a dramatic effect on the stiffness and ductility ratio of the bolted joints.